Automatic apparatus for detecting smoke and the like.



- NT DP 3.410. DA I PATH E E ,98

AUTOMATIC APPARATUS F OR DETECTING SMOKE AND THE LIKE.

APPLICATION FILED DBO. 6. 1907- 3 SHEETB-SHEE'I' 1.

A y? f i i M No. 878,456. PATENTED FEB 4, 1908. H. DARWIN.

AUTOMATIC APPARATUS FOR DETECTING SMOKE AND THE LIKE.

APPLICATION FILED DBO. 6. 1907.

3 SHEETSSHEET 2.-

A M I312, 5 E W w [III/II.

AUTOMATIC APPA APPLICATION FILED DEU- 6 1907.

- PATENTBD FEB. 4, 1908.

H. DARWIN. RATUS FOR DETECTING SMOKE AND THE LIKE.

3 SHBBTB-BHELT 3.

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' the foll ence the relay is brought'into action and HORACE DARWIN, OF CAMBRIDGE, ENGLAND.

AUTOMATIC APPARATUS FOR DETECTING SMOKE AND THE LIKE.

Specification of Letters Patent. Application filed December 6 1907. Serial N 0. 405,456-

Patented Feb. 4, 1908.

To all whom it may concern: I

e it known that I, HORACE DARWIN, a subject of the King of England, residing at 1 Cambridge, in En land, have invented certain-new and use 1 Automatic A'p aratus for Detecting Smoke and the Like, 0 which owing is a s ecification. The object of t is invention is to give warning automatically of the smoky condition of a flue or chimney, by causing a bell I to be rung or other signal to be operated as soon as the smoke has become more dense than is permissible.

arm signal apparatus according to this invention, comprises a source of luminous or thermal radiation, the radiation from the source being made to traverse a column 1 of the smoke to be tested before falling upon devices sensitive to radiation. The said sensitive devices are so connected with a suitable relay that the relay is brought into operation and causes a signal to be given as soon as the proportion or percentage of incident radiation absorbed by the column of smoke exceeds a certain predetermined value.

In order to eliminate uncertainties which I might arise from variations in the intensity of the source of radiation, it is preferred to allow two beams from the same source to fall upon the said sensitive devices the disposition of the apparatus being such that one only of the beams has traversed the smoke-column while the effects produced upon the sensitive devices by the two beams are opposed to one another. The adjustments of the apparatus may then be so: made that when the mutually opposing influences of the two beams just balance and l counteract one another, the relay is not brought into action while as soon as that beam which has not passed through the smoke column exerts a predominating influi causes a signal to be given. That portion of chimney-smoke which lies in the path of the radiant beam aforesaid or alternatively in the path of one of the two radiant beams, and which has been referred to as the smokecolumn may be momentarily contained in a special] constructed chamber which forms part 0 the alarm signal apparatus and through which smoke from the chimney is made to circulate. Or the smoke-column mav consist of smoke within the chimney} or'flue the source of radiation and devices sensitive to radiation being suitably. dischimney.

In apparatus according to this invention it is advantageous b means of lenses or mirrors to render parahel the beam or beams which have proceeded radiation so that for example that beam which traverses the smoke-column is approximately a parallel beam while the beam or beams are preferably converged by means of lenses or mirrors upon the sensitive devices.

In a convenient construction according to this invention the source of radiation is of high intrinsic brightness, the glowing filament of a N ernst electric lamp having been found to be suitable. The radiation from the said source is rendered approximately parallel by passing through a condensing lens and is then caused to 'pass lengthwise through a long box which is divided by a lengthwise partition into two compartments. One of these compartments hereinafter called the air-chamber contains only atmospheric air while the other compartment hereinafter called the smoke-chamber contains sn'ioke fron the chimney or flue to be tested, the stnoke being caused to circulate from the chimney to the smoke-chamber, through the smoke-chamber and finally either back to the chimney or to the outer air. The smoke is preferably cooled before entering the smoke-chamber and such cooling is conveniently effected by causing the smoke after leaving the chimney to pass downwards through a pipe cooled by water. The smoke exhausted from the smoke-chamber may then be led back into the chimney at a point lower than that at which the pipe supplying the smoke-chamber leaves the c irnney. A circulation of smoke through the smoke-chamber is thus promoted and pumping devices for maintaining a circulation of the smoke are in some cases rendered unnecessary.

At the end of the aforesaid long box remote from the source of radiation two converging lenses are so placed that through one of the lenses passes the radiant beam. which has traversed the smoke-chamber while through the other lens passes the radiant beam which has traversed the air-chamber. By means of these two convergi g lenses, two separate from the source of -radiation are arranged in a images of the source of radiation are formed and a thermo-pilc is so placed that one of the images is focused upon one set of junctions while the second of the images is sinilarly ri'ocused upon one set of junctions of a second thermo-pile. The two the1n1o-p1les are joined in simple series with one another and with a galvanometer, the order of the connections. being such that the electromotive forces arising from the heating of the thermo junctions bythe two images are opposed to one another, When a glowing Nernst lamp filairent or other narrow body is used as the source of radiation, the therno-piles are preferably of linear form, that is to say in each them 0- pile the junctions which are to receive the straight line and the corresponding l-\ age of the source of radiation is projected so as to cover them.

The deflectable member of the galvanom-.

eter carries a projecting'boom which is swept around 1n one or other direction according to the direction of the current which passes through the galvanometer, that is to say accordmg as the heating efl'ect of the one or the other image of the radiant soure produces the predominant electromotive force in the circuit.

By suitably controlling the two radiant beams as for example by introducing an adjustable diaphragm in the path of that beam which traverses the air-chamber the apparatus can be so adjusted that the electromotive 'i'orces arising from the two thermo-piles will just balance and counteract one another when the denseness of the smoke within the smoke chamber is such as corresponds to the greatest permissible denseness of smoke in the chimney. In this case it is evident that the electromotive force due to the effect of that radiant beam which has passed through the air-chamber will be predominant when and only when the permissible denseness of smoke in the chimnev is exceeded. As soon 1 as the galvanometer boom is deflected even slightly in the direction corresponding to an excessive denseness of smoke it causes a relay to be actuated and a signal to be'given. For example a relay may be-used of which a description was recently published. In this case the galvanometer boom'when deflected in the direction corresponding to excessive smoke-density becomes engaged in suitably formed teeth upon the periphery of a wheel which is kept slowly rotating by clockwork. Once the boom has become engaged with such a wheel the boom follows the peripheral motion of the wheel for the greater part. of

one revolution and after that the boom is free to recede from the wheel or to become once more engaged with the teeth of the wheel according to the direction of the current which is at that moment flowing through the galvanometer. While the galvanometer weight in such manner a ed with the teeth of the rotating boom is en 0 wheel as a oresald it is caused to rub against two spring-controlled strips or brushes so as to close an independent electric circuit and thus cause a bell to be rung or other signal to be given. To enable the galvanometer boom when engaged with the teeth of the wheel to follow the peripheral motion of the wheel without damage to the suspension'of the galvanometei' the boom is connected by a pivot to the defiectable member of the galvanometer the axis of the pivot bein perpendicular to the axis of freedom of t e deilectable member. The galvanometer boom is moreover controlled for example by a that as soon as dis engaged from the teeth of the aforesaid wheel the boom turns about the ivot until iinite stop. It is preferable to maintain throughout the smoke-circulation and especially within thesmoke chamber a pressure slightly below that of the atmosphere the aforesaid condensing and converging lenses being so placedthat. their cells very nearly but not quite close the respective ends of the smoke-chamber and air-chamber. In this case it is evident that atmospheric air will enter slowly through the chinks between the ends of the chambers and the cells of the lenses and will thus hinder the deposition of soot from the lenses. When atmospheric air is thus drawn into the apparatus past the lenses it is desirable that such air should be filtered sothat it may not be charged with coal-dust or the like which would form deposits upon the lenses. Filtration of the air may be efl'ected for example by inclosing in adust-tight box a portion of the apparatus comprising the source oi'radiation lenses, smoke chamber, air-chamber and thermo-piles the said box being provided with a window or windows of a material such as felt. I

In the accompanying drawings Figures 1 and 1 is a sectional elevation showing essential parts of one form of apparatus constructed according to this invention and Fig. 2 is a diagrammatic view of the electrical circuits and connections.

Like parts are indicated by like reference letters in the two figures.

In Fig. 1 and 1"v A is aNernst lamp whereof the filament A when rendered incandescent is use'd as a source of being adjustably supported by a bracket A provided with pine ing screws A. The

radiation the lamp A ney or smoke-chamber B and B is a pi e by which the smoke can leave the smo e-chamber. The smoke before entering the smoke-chamber by the pipe B is preferably cooled for exi ample by causing it to descend through a )ipe externally cooled by water. The pipe 5 may conveniently lead back to the chimfiue whence the smoke sample was derived. smoke through the smoke-chamber cannot be secured by gravity in the manner hereinbefore mentioned a fan steam ejector or other like device is intrbduced into the course of the pipe B.

D D are two converging lenses mounted in a common cell D which 1sattached to the body B.

' E E are two sets of thermo-electric junctions the arrangement ofwhich is hereinafter described in connection with Fig. 2.

S E are terminals in electrical connection with the respective ends of the thermo-electric system E E.

E is an insulating piece which carries the thermo-electric system E E and the terminals E E.

E E are supports which are fixed to the body B and which carry the insulating piece E F is a thin window of fiat glass interposed betweenthe lenses C C and the body B. The window F is so mounted as to be capable of sliding in its own plane so that it can be withdrawn laterally to a sufficient extent to allow of it s being readily cleaned. The win dow F is moreover of such a length in the direction of its sliding freedom that when it is drawn out for cleaning purposes the lenses C C are still protected by the window F from smoke which may be contained in the smoke-chamber B.

F is a window similar to F and for a like purpose. 7

Radiation proceeding from the lamp-filament A isrendered approximately parallel by passing through lenses'C C The beam then traverses the windows F F without sensible deviation and is converged to form two separate images of the filament A by the lenses D D. Where the said two images are formed the respective sets of thermo-electric junctions E E are set. A screen or diaphragm not shown in the drawings can be adjusted to such a position between the lens D and the thermo-electric junctions E that the electromotive forces arising from the heating of these two sets of junctions just neutralize one another when the denseness of smoke within the smoke-chamber is such as corresponds to the greatest permissible density of smoke within the chimney.

G is a cover which can be secured upon the base G so as to cover the apparatus in a dusttight manner.

G G are windows of felt or the like closing When a sufficient circulation of holes in the cover G so that air freed from dust can be drawn into the apparatus as hereinbefore mentioned.

To enable accumulations of soot to be removed from the smoke-chamber B suitable opinings capable of being closed in a dustt1 sri ioke-chamber B. Access to the interior of the chamber B being gained by uncovering the said openings the soot from the chamber can be swept into the pipes B B and on removing the caps BPB from the ap aratus. Provision may also be made for s utting ofl' communication between the pipes B B and the smoke-chamber B and for blowing steam or compressed air through the said pipes so as to clear them of soot Alternatively in place of the aforesaid openings in the walls of the smoke-chamthe lens-systems G C and D D may be made removable so as to allow of access to the interior of the smoke-chamber B. For example a single supportcarrying the lamp A and the condenser C C may be so hinged to one end of the body B as to be capable of being swung outward for cleaning purposes and readily returned to a perfectly definite position in which it can be secured by a screw 0nd support similarly hinged and similarly returnable to a definite position in which it.

can be secured may be made to carry the lenses D D in their cell D together with the thermo-electric system E E E E E When "the said hinged supports are employed those faces of the lenses 0 D WlllCh are presented towards the smoke-chamber B are rendered accessible for cleaning so that the windows F F may be dispensed with.

Referring now to Fig. 2, E represents one set of thermo-electric junctions on which is focused an image of the incandescent filament formed by radiation which has traversed the smoke-chamber aforesaid. E represents the complementary set of thermoelectric j u'nctions on which is focused an image of the incandescent filament formed by radiation which has traversed'the air-cham- The metals from tric system E E which the thermoelec is formed may be any two which constitute a pair of high thermo-electric power. For example, one of the metals may be copper and the other an alloy of coppier and nickel in about equal parts byweight. he metals are preferably drawn in the form of fine'wires w 'ch are afterwards flattened by rolling into thin narrow strips. In place of a single thermopile such as E E it is sometimes preferable to use two distinct thermo-piles sup orted so as to be adjust able independently of one another. 1n this case ipnly one set of junctions of each ther mop thermopiles are joined in series with the galvat manner may be made in the walls of the Y can be discharged A or other locking device. A sece is exposed to radiation and'the two electric system E E case the pointer nometer the connections being such that the forces-arising from the heating of the thermojunctions by the two images of the glowing filament are opposed to one another.

H is the coil of a moving-coil galvanometer so connected in series with the thermothat when the heating roduces the predomiorce in the circuit, the

clock-wise deflecof the junctions E nant electro-motive resulting current causes a tion of the coil H and pointerH. In that 11 leaves the fixed sto K and approaches the wheel L between which and the spring-controlled brushes L L the ointer H becomes engaged. The pointer I is of metal but is insulated from the coil II so that the simultaneous contact of the brushes L L with the said pointer suliices to complete electrically a circuit comprising the battery M and electric bell N. It is thus evident that if the denseness of the smoke in the aforesaid smoke-chamber exceeds the permissible limit in accordance with which the apparatus has been adjusted, the electric bell N will be caused to ring.

What I claim as my invention and desire to secure by Letters Patent is 1. In an apparatus of the'character described, the combination of a source of radiation, means sensitive to radiation and adapted to receive the rays from said source,

'means for interposing the smoke in the path while leaving the pasof some of said rays, sage of the remaining rays unobstructed, and means actuated by said ray-receiving means adapted to sound an alarm when the smoke exceeds a certain denseness.

2. In automatic ap aratus for detecting smoke and the like, tie combination of a source of radiation placed so as to radiate through a sample of the smoke to be tested and balanced devices sensitive to radiation and having a part placed so asto'receive radiation which has emanated from the said source and passed through the said smokesample whereby the said devices are unbalanced.

3. In automatic apparatus for detecting smoke and the like, the combination with a source of radiation, an element for gathering such radiation into a parallel beam, means for interposing in the path of such parallel beam a sample of the smoke to be tested, an

.by a partition B into two chambers element for reconcentrating the parallel beam to form an image of the said source of radiation, devices sensitive to radiation placed so as to receive the image, and alarm apparatus operatively connected with the said sensitive devices and adapted to give a signal automatically when the denseness of the smoke-sample exceeds its greatest permissible value.

4. In automatic apparatus for detecting smoke and the like, the combination of a source of radiation A, an adjustable support for said source of radiation, a condensing lens system C C, a box B divided lengthwise by a partition B into two chambers B B pipes B B leading respectively to and from the chamber B and communicating with the source of smoke to be tested, lenses D D in the chambers B B respectively, two sets of thermo-electric junctions E E adjustably supported so as to receive the two images of the source of radiation formed by the lenses D D and a galvanometer connected in se-- ries with the two sets of thermo-electric 1unctions.

5. In automatic apparatus for detecting smoke and the like, the combination of a source of radiation A, an adjustable support for said source of radiation, a condensing lens system 0 G a box B divided lengtilgiwligse 1 2 7 pipes B B leading respectively to and from the chamber B and communicating with the source of smoke to be tested, lenses D D in the chambers B and B respectively, two sets of thermo-electric junctions E E adjustably supported so as to receive the two images of the source of radiation formed by the lenses D D, a galvanometer connected in series with the two'sets of thermo-electricjunctions, and a relay capable of being operated by the deflection of the galvanometer so as to cause a signal to be iven automatically when the denseness of t 1e smoke-sample exceeds its greatest permissible value.

In testimony whereof I have signed my name to this specification in the presence of Witnesses:

HARRY B. BRIDGE, HERBERT BURRAGE. 

